Gama-aminobutyric acid (γ-aminobutyric acid), also named GABA, is a nonproteinous amino acid, derived from glutamate and ornithine through metabolic pathways in living organisms. GABA is enriched in the vertebrate central nervous system, which is one of the mayor inhibitory neurotransmitters in the mammal central nervous system. The binding of GABA to the receptor GABAA on the neuron triggers the opening of the chloride ion selective pore to reduce the effect of excitatory neurotransmitters, resulting in inhibition on neurotransmission. In addition, the binding of GABA to the receptor GABAB triggers the opening of the potassium ion channel and presynaptic calcium ion channel to allow positively charged ions to move out from the neuron, resulting in inhibition on neurotransmission. Thus, GABA has a function which inhibits the overexcited central nervous system and stabilizes the brain. In clinical, GABA has been known for being used in the prevention or treatment of depression and insomnia and stabilizing blood pressure.
The well-known methods for producing GABA are based on biosyntheses. For instance, King H. K. et al provides a method for producing GABA by culturing Wilson's Bacterium coli Type I in a casein-hydrolysate glucose medium (King K. H. & Fletcher L. I., The Production of γ-Aminobutyric Acid by Bacterium coli Wilson, Type I, Microbiology-sgm, vol. 4, no. 2, p. 238-241, 1950). Recently, Guo X. F. et al has provided a method for producing GABA by a marine yeast isolate Pichia anomala MR-1 strain by using a solution containing monosodium glutamate and glucose and culturing at 40.5˜48.0° C. (Guo X. F., et al., Optimal Reaction Conditions for Production of γ-Aminobutyric acid by the Marine Yeast Isolate Pichia anomala MR-1 Strain, Biosci. Biotechnol. Biochem., 75(10), 1867-1871, 2011).